African PREDICT study (African Prospective study on the Early Detection and Identification of Cardiovascular Disease and Hypertension) is an ongoing study held at the North-West University, Potchefstroom, South Africa (Strauss et al, 2017). We included 331 apparently healthy participants from that study (20-30 years) (42.9% black, 43.8% men) on a habitual diet. Notably, that the participants consumed relatively high sodium chloride amount on a daily basis: in average 6.5 g/24hr for women and 8.5 g/24hr for men, both black and white. We obtained 24hr and central SBP, and 24hr urinary Na+ and MBG levels. We found no ethnic differences in MBG, Na+ or MBG/Na+. MBG excretion correlated positively with Na+ excretion in all groups and to SBP in white men and black women (p<0.011). In black women only SBP related positively to MBG/Na+ in single and multi-variable adjusted regression models: central SBP (R-squared=0.26; beta=0.28; p=0.039), 24hr SBP (R-squared=0.46; beta=0.30; p=0.011), daytime (R-squared=0.38; beta=0.28; p=0.023) and nighttime SBP (R-squared=0.38; beta=0.33; p=0.009). In contrast, inverse associations of MBG/Na+ with nighttime SBP were evident in white women (r= -0.20; p=0.038) but lost significance after multiple adjustments (R-squared=0.36; beta= -0.13; p=0.12). We found independent positive associations of SBP with MBG/Na+ in black women. This data supports the concept that reduced MBG-mediated Na+ excretion can contribute to adverse hemodynamics. In conclusion, in young black women the MBG/Na+ excretion ratio associated with an increase in cSBP, 24hr SBP and stroke volume which might reflect an increased cardiovascular risk due to abnormal sodium handling. Conversely, the inverse correlation between MBG/Na+ and nighttime SBP in young white women supports the concept of the expected natriuretic effect of MBG in a young healthy population.